Variable condenser



J. w. SIMMONS VARIABLE CONDENSER April 23, 929.

Filed Aug. 4. 1922 Shee't5-SheetI l @WwW/0f' fr MW (KM @/WMN W M H ril/UM wm, H1 fw Llml H ai? f 3 M H M, 7M u a,

J. W. SIMMONS VARIABLE CONDENSER Apri Filed Aug. 4. 1922 5 Sheets-Sheet @yad - designated 11.

Patented Apr. 23, 1929.

UNITED A s'mras l 1,799,959 PATENTv OFFICE.

JOHN W. SIMMONS, OF CLEVELAND, OHIO, ASSIGNOR T RADIO CORPORATION OF AMERICA, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

VARIABLE coNDENsER.

Application med August 4, 1922. sieriaifml. 579,625.

This invention relates generally to radio apparatus and more particularly to a novel construction of variable Condenser employed as a part of said apparatus. The object of the invention is to provide a simple and highly etlicient construction of device in which' great rigidity and consequently accuracy of tixedness is obtained. Another object of the invention is to provide for quick and easy movement of the movable plates into and out of stationary plates and a still further object is to provide an auxiliary means for obtainingexceedingly iine 'adjustments or movements of the movable plates with reference to the stationary plate, such auxiliary means being provided with stop means to prevent undue ymovement of the movable plates in either direction.

With this and other objects in View. which will be hereinafter more fully set forth, the invention consists in the novel features of yconstruction and in the manner of combining or arranging the same, all of which will be described hereinafter and pointed out in the r appended claims.

In the drawings forming a part of this specification Fig. 1 is a front elevation of a variable condenser constructed in accordance with my invention; Fig. 2 is a side elevation looking at the same from the right hand side; Fig. 3 is a side elevation looking from the lett hand side; Fig. is a sectional view on the line 4-4 of Fig. 1; Fig. 5 is a vertical sectional view on the line-5 5 ofiFig. 2; Fig. (S is a rear elevation; Fig. 7 is a sectional view on the line 7 7 of Fig. 4; Fig. 8 is a detail sectional vview similar to Fig. 5, but showing the movable plates turned entirely' clear of the iixed plates; Fig.- 9 is a sectional view of one of the spacing posts and Fig. 10 is a detail sectional view on the line 10-10 of Fig. 9. In constructing a variable condenser for radio apparatus it is usual to employ a plurality or' spaced stationary plates and between which are moved the series of spaced movable plates in order to increase or decrease the capacitance of the condenser and to that exi tent my invention involves the same general arrangement-alie stationary plates being designated 1() and the movable plates being These fixed and movable plates are arranged between an inner plate 12 and an outer plate 13 which with suitable connecting posts constructed as hereinafter more fully explained constitute a frame which is connected to a portion 14 of the casing of the radioapparatus, this casing being preferably formed from any well known dielectric material.

It is of the utmost importance that the stationary plates should be accurately spaced and that the movable plates should be accurately spaced also, not only with reference to one another, but with reference to the fixed plates so that they can move freely in and out between said fixed plates without contacting therewith. Heretofore it has vbeen commonpractice to employ spacing washers between the supported ends or corners of the fixed plates and likewise between the ends or corners ofthe movable plates, but it is practically an impossibility to obtain absolute uniformity in therg thickness of the spacing washers and consequently great ditliculty has been encountered in assembling the parts of the vari able condensers due to this almost imperceptible inequality in the thickness of the spacing washers. One of the principal objects of my invention is to overcome this difficulty and this I do by a novel construction of combined spacing and connecting post which comprises a tube 15 in which slots 16 are cut, these slots being produced exactly equal distances apart and they extend nearly through the tube as most clearly shown in Figs. 9 and 10. The fixed plates are shaped as shown in Fig. 8 and at spaced points are formed with bifurcated extensions 10a which are inserted in the slots 16 of the tubes 15 and then after being properly positioned the rods or pins 17 are passed longitudinally through the tubes 15 and transversely through the bifurcated ends of the plates 10. These rods or pins 17 not only pass through the stationary plates 10, but also through the inner and outer plates 12 and 18 and nuts 18 screwed upon the ends thereof serve to securely fasten together the various parts of the frame and if desired,v spacing collars or nuts may be employed between the ends of the tubes and the plates 12 and 13. In this manner the plates 12 and 13 are securely connected together and the fixed condenser plates 10 are quickly, easily and accurately spaced attheir corners or edges and it is obvious that no displacement can take place so long as the rods or pins 17 are within the tube inasmuch as they also engage the bifurcated ends of the fixed plates and prevent any movement in one direction or another. It is obvious that the ends could be perforated if it were desired, but bifurcation answers all practical purposes and so long as the pin passes transversely through the plates and longitudinally through the transversely slotted tube, no disconnection of the parts can be had at these points. The movable plates are fixed at their pivotal end in a tube which is transversely slotted at 21 in exactly the same manner as the tubes 15. The movable plates 11 are formed with a slight extension 112L which is apertured and this apertured extended end is inserted in the slot of the tube 2O and a shaft 22 passes through the outer plate 13 and through the tube 2O and seriesof plates 11 and has its reduced end 22;l

. extending through an insulating bushing 23 fixed in the inner plate 12. A nut 24 is screwed upon the threaded reduced portion of the shaft for the purpose of securely cennecting the tube and plates thereto, therebeing an enlargement 22b upon the opposite end of the shaft adjacent the outer plate 13.

A coil spring 25 surrounds the reduced end 22"x of the shaft and tends to hold the said shaft so that the movable plates are maintained in proper relation to the fixed plates and so that the enlarged portion 22b will contact with the operating toothed segment and hold the same in proper position against the outer plate as hereinafter more clearly set forth. The opposite ends of movable plates are secured in a tube 26, slotted transversely as previously described, the ends of the movable plates being apertured to receive the securing bolt or pin 26a which has the nuts 27 screwed upon the opposite ends thereof. By

- connecting the series of fixed plates in the manner herein described, it is obvious that they are accurately spaced with very little difficulty in the assemblage and that 'the movable plates are also accurately spaced with reference to each other and by properly positionin g the rotary shaft 22 the movable plates cau be readily positioned with reference to the fixed plates so that they can move freely in and out. A hand wheel 28 is fixed upon the outwardly extending end of the shaft 22 and carries in connection therewith a graduated dial 29. By turning the hand wheel the shaft 22 will be rotated and carry with it the movable plates.

Connected to the shaft 22 and held between the outer plate 13 and the enlargement 22b is the mutilated gear 30 which meshes with a gear 31 mounted upon the inner side of the plate 13. This gear 31, in turn meshes with a pinion 32 which is carried at the inner end of a shaft 33 which passes outwardly through the casing and is provided with a hand wheel 34. It will be noted that by reference to Fig. 4 and likewise Fig. 7 that the gear 31 is provided with an overhanging peripheral flange 31 which maintains the pinion 32 and the gear 30 all in their proper plane and in operative engagement with the gear 31.

when the approximate proper adjustment has been obtained the hand wheel 34 can be moved in the proper direction and owing to the reduction in gearing between the gears 31 and 32 and likewise the tooth'ed portion 30 of the disk 30 it is obvious that a very fine adjustment can be obtained. That is to say, an adjuksltment equal to a vernier adjustment is possi e.

The shaft 22 is insulated from the plate 12 but this plate 12 is provided with a bindingr post 34 and also a binding post 35, but the binding post 35 is also insulated from the plate 12 and a wire 36 connects the binding post to the extended reduced end 221 of the shaft, this wire being coiled several times around the extended end of the shaft so that the rotary movement of the shaft will not tend todisrupt the connection between the extended end of the shaft and the binding postJ 35.

In practice I prefer to make the last tooth of the segment 30L1 cut away on a radius as indicated at 30b so that if the hand wheel 28 is turned forcibly in veither direction this cut away portion 3()b coming in contact with the teeth of the gear 31 will serve as a stop and prevent any injury due to the sudden stoppage of the movement and Will also prevent dislocation of the gear and toothed segment.

It will thus be seen that I provide a simple and highly efficient form of variable condenser in which the fixed plates are quickly and easily and accurately spaced with reference to each other and in which. the movable plates are likewise accurately spaced. It will also be noted that the movements of the movable plates are quickly and easily obtained and furthermore that exceedingly line adjustments are possible.

The device as a whole is extremely rigid, thereby maintaining the various parts fixed in their proper spaced relations.

Having thus described my invention, what I claim is:

1. In a device of the kind described, the combination with a pair of frame plates, of a plurality of fixed condenser plates and a plurality of movable condenser plates, the ends of the fixed plates being positioned in parallel slots cut into and partly through tubular posts and tie rods passing longitudinally through said tubular post and transversely through the stationary plates, the ends of the movable plates being inserted in the parallel slots of a tubular post and a shaft passinnf longitudinally through said tubular post ant transversely through thel ends of the movable plates together with means for positioning said shaft in the frame plates and means for moving the same.

2. In a device of the kind described, the

combination with the frame plates, of tubular posts connected thereto, said tubular posts being transversely slotted in parallel order. the fixed plates having their ends bifurcated and inserted in the parallel slot in the tubular posts, tie rods passing longitudinally through the tubular posts and transversely through the bifurcatcd ends of the fixied plates, the movable plates and the slotted post in which the apertured ends of said plates are inserted and a shaft passing through said tubular post and through the apertured ends of the movable plates, a gear mounted upon said shaft and a gear of less diameter meshing with the first named gear and adapted to operate the same.

3. In a device of the kind described, the combination with the frame plates, of the fixed condenser plates and the movable condenser plates, fixed ltubular posts and parallel slots, the' ends of the fixed plates fitting in said slots, the tie rods passing through the fixed posts, fixed plates and frame plates, a movable post having parallel slots, perforated ends of the movable plates being inserted in said slots, a rotary shaft passing through the frame plates, movable plates and rotary post, the inner end of said rotary shaft being reduced and threaded, a nut screwed upon said reduced end and contacting with the rotary post, a coil spring interposed between the frame plate and said nut and uniting the reduced end of the rotary shaft, said reduced and extended end of said shaft having a circuit Wire connected thereto.

4. In a device of the kind described, the combination with the frame-plates, fixed condenser plates and movable condenser plates, of the fixed slotted tubular posts and the movable slotted tubular posts, the ends of the fixed plates being inserted in the slots of the fixed posts and tie rods passing through the frame plates, fixed posts and fixed plates, a rotary shaft passing through the movable post and through the ends of the movable plates, the inner end of said rotary shaft being reduced and projected through one of the frame plates and through an insulated bush` ing carried by said plate, 'a mutilated gear fixed upon said rotary shaft, a hand wheel fixed upon the outer end of said shaft, a pinion, a shaft carrying said pinion and provided With a hand Wheel anda gear between the pinion and the mutilated gear as set forth.

In testimony whereof, I hereunto affix my signature.

JOHN W. SIMMONS. 

